Add a workaround for simulate secondary display

To workaround a deadlock caused by bufferqueue locks
we force RenderThread over to use async mode which
we enable via eglSwapInterval(0)

Bug: 38372997
Test: steps in the bug
Change-Id: Ia305f73abbdd64ab0c25d1f7d32792cc6295a0ce
diff --git a/libs/hwui/renderthread/RenderProxy.h b/libs/hwui/renderthread/RenderProxy.h
index b21772c..6f4e8ce 100644
--- a/libs/hwui/renderthread/RenderProxy.h
+++ b/libs/hwui/renderthread/RenderProxy.h
@@ -137,6 +137,8 @@
     static int copyGraphicBufferInto(GraphicBuffer* buffer, SkBitmap* bitmap);
 
     static void onBitmapDestroyed(uint32_t pixelRefId);
+
+    ANDROID_API static void disableVsync();
 private:
     RenderThread& mRenderThread;
     CanvasContext* mContext;